Bone anchoring device, tool and method for assembling the same and tool for use with the same

Abstract

A bone anchoring device includes an anchoring element having a shaft for anchoring in the bone and a head, a receiving part formed in one piece, and a pressure element formed in one piece. The receiving part has a seat for receiving the head and an outer channel for receiving a rod to be connected to the anchoring element, which is pivotable with respect to the receiving part and can be fixed at an angle by exerting pressure via the pressure element onto the head. The pressure element is movable in the receiving part and includes an inner channel for receiving the rod and a spring element that engages a portion of the receiving part via a detent connection so that the pressure element can be held in a position that allows pivoting of the anchoring element. The spring element is formed by at least a first portion of one of two side walls forming the inner channel, the first portion being spaced apart from a second portion of the one side wall by a slot. At least a portion of the detent connection is located on the one side wall.

What is claimed is: 
     
       1. A bone anchoring device comprising:
 an anchoring element having a shaft for anchoring to a bone and having a head; 
 a receiving part formed in one piece, the receiving part comprising a seat for receiving the head and a channel for receiving a rod to be connected to the bone anchoring device; 
 a pressure element formed in one piece, the pressure element being movable in the receiving part to exert pressure onto the head when the head and the pressure element are in the receiving part; and 
 wherein the anchoring element is pivotable with respect to the receiving part and is configured to be fixed at an angle by exerting pressure via the pressure element onto the head; 
 wherein the pressure element comprises a substantially U-shaped recess defining two side walls to receive the rod therebetween; 
 wherein the pressure element further comprises a spring element on each of the two side walls, each spring element being monolithic with an outer wall portion of a respective side wall and comprising a detent portion configured to engage a portion of the receiving part so that the pressure element is configured to be held in a position that allows pivoting of the anchoring element; and 
 wherein each spring element on a first the outer wall portion of its respective side wall is spaced apart from an inner wall portion of its respective side wall by a slot. 
 
     
     
       2. The bone anchoring device of  claim 1 , wherein the receiving part comprises a recess formed at an inner wall of the receiving part and wherein, for at least one of the spring elements, the detent is configured to be resiliently depressed radially inward into the slot and to engage the recess. 
     
     
       3. The bone anchoring device of  claim 2 , wherein, for the at least one spring element, the detent is shaped asymmetrically with respect to a direction of movement of the pressure element so as to allow assembly of the pressure element in the receiving part and to inhibit disassembly of the pressure element from the receiving part. 
     
     
       4. The bone anchoring device of  claim 3 , wherein, for the at least one spring element, the detent comprises an edge that is configured to abut a wall defining the recess formed at the inner wall of the receiving part. 
     
     
       5. The bone anchoring element of  claim 2 , wherein, for the at least one spring element, the detent is symmetrical with respect to a direction of movement of the pressure element to allow assembly and disassembly of the pressure element to and from the receiving part, respectively. 
     
     
       6. The bone anchoring device of  claim 1 , wherein, for at least one of the spring elements, the slot is defined by a top surface and a bottom surface at opposite ends along an axis in a direction of a central axis of the pressure element, wherein the slot is closed at the top surface and/or the bottom surface. 
     
     
       7. The bone anchoring device of  claim 6 , wherein, for the at least one spring element, the slot is closed at the bottom surface. 
     
     
       8. The bone anchoring device of  claim 1 , further comprising a rod, wherein the two side walls each have free ends, wherein the free ends are each configured to extend beyond the rod when the rod is received in the U-shaped recess and wherein, for at least one of the spring elements, the slot extends beyond the rod on its respective side wall when the rod is received in the U-shaped recess. 
     
     
       9. The bone anchoring device of  claim 1 , wherein the receiving part comprises a first bore for passing the shaft of the anchoring element therethrough and a second bore for introducing the shaft and the head. 
     
     
       10. The bone anchoring device of  claim 1 , wherein a locking device is provided that is configured to cooperate with the receiving part to lock the head and the rod separately when the head and the rod are in the receiving part. 
     
     
       11. The bone anchoring device of  claim 1 , wherein a locking device is provided that is configured to cooperate with the receiving part to lock the head and the rod simultaneously when the head and the rod are in the receiving part. 
     
     
       12. The bone anchoring device of  claim 1 , wherein, for at least one of the spring elements, the slot extends to an exterior surface of the pressure element. 
     
     
       13. A bone anchoring device comprising:
 an anchoring element having a shaft for anchoring to a bone and having a head; 
 a receiving part formed in one piece, the receiving part comprising a seat for receiving the head and a channel for receiving a rod to be connected to the bone anchoring device, the channel formed by an inner wall and the inner wall defining a bore; 
 a pressure element formed in one piece, the pressure element being movable in the receiving part and configured to exert pressure onto the head when the head and the pressure element are in the receiving part, the pressure element comprising a substantially U-shaped recess defining a bottom and two side walls to receive the rod therebetween; and 
 wherein the anchoring element is pivotable with respect to the receiving part and is configured to be fixed at an angle by exerting pressure via the pressure element onto the head; 
 wherein the pressure element further comprises a spring element on an outer wall portion of one of the side walls, the spring element spaced apart from an inner wall portion of the one side wall by a slot, the spring element having a detent that protrudes from the spring element toward the inner wall of the receiving part when assembled in the channel of the receiving part; 
 wherein the spring element is movable from a first position wherein the spring element is unlocked from the receiving part, to a second position wherein the spring element is locked to the receiving part via the detent of the pressure element being located in the bore of the receiving part, wherein in the second position the pressure element is held in a position that allows pivoting of the anchoring element; and 
 wherein at least a portion of the detent is located above the bottom of the U-shaped recess. 
 
     
     
       14. The bone anchoring device of  claim 13 , wherein the entire detent is located above the bottom of the U-shaped recess. 
     
     
       15. A method of assembling a bone anchoring device using a tool, the bone anchoring device comprising:
 an anchoring element having a shaft for anchoring to a bone and having a head; 
 a receiving part formed in one piece, the receiving part comprising a seat for receiving the head and a channel for receiving a rod to be connected to the bone anchoring device, the channel formed by an inner wall and the inner wall defining a bore; 
 a pressure element formed in one piece, the pressure element being movable in the receiving part to exert pressure onto the head when the head and the pressure element are in the receiving part, the pressure element comprising a substantially U-shaped recess defining a bottom and two side walls to receive the rod therebetween; and 
 wherein the anchoring element is pivotable with respect to the receiving part and is configured to be fixed at an angle by exerting pressure via the pressure element onto the head; 
 wherein the pressure element further comprises a spring element on an outer wall portion of one of the side walls, the spring element spaced apart from an inner wall portion of the one side wall by a slot, the spring element having a detent that protrudes from the spring element toward the inner wall of the receiving part when assembled in the channel of the receiving part; 
 wherein the spring element is movable from a first position wherein the spring element is unlocked from the receiving part, to a second position wherein the spring element is locked to the receiving part via of the pressure element being located in the bore of the receiving part, wherein in the second position the pressure element is held in a position that allows pivoting of the anchoring element; and 
 wherein at least a portion of the detent is located above the bottom of the U-shaped recess, and 
 the tool comprising a base portion and a dummy rod portion, the dummy rod portion being connectable to the pressure element, 
 the method comprising the steps: 
 arranging the tool in a position in which the dummy rod portion is exposed from the base portion; 
 connecting the dummy rod portion with the pressure element; 
 placing the receiving part onto the pressure element; and 
 pressing the receiving part against the base portion until the spring element engages the receiving part. 
 
     
     
       16. A method for inserting a bone anchoring device into a bone using a tool, the bone anchoring device comprising:
 an anchoring element having a shaft for anchoring to a bone and having a head; 
 a receiving part formed in one piece, the receiving part comprising a seat for receiving the head and a channel for receiving a rod to be connected to the bone anchoring device, the channel formed by an inner wall and the inner wall defining a bore; 
 a pressure element formed in one piece, the pressure element being movable in the receiving part to exert pressure onto the head when the head and the pressure element are in the receiving part, the pressure element comprising a substantially U-shaped recess defining a bottom and two side walls to receive the rod therebetween; and 
 wherein the anchoring element is pivotable with respect to the receiving part and is configured to be fixed at an angle by exerting pressure via the pressure element onto the head; 
 wherein the pressure element further comprises a spring element on an outer wall portion of one of the side walls, the spring element spaced apart from an inner wall portion of the one side wall by a slot, the spring element having a detent that protrudes from the spring element toward the inner wall of the receiving part when assembled in the channel of the receiving part; 
 wherein the spring element is movable from a first position wherein the spring element is unlocked from the receiving part, to a second position wherein the spring element is locked to the receiving part via the detent of the pressure element being located in the bore of the receiving part, wherein in the second position the pressure element is held in a position that allows pivoting of the anchoring element; and 
 wherein at least a portion of the detent is located above the bottom of the U-shaped recess, and 
 
       the tool comprising:
  a drive member rotatably connected to a counter-holding member, wherein the drive member is sized to extend through the counter-holding member and the receiving part into a head recess on the head, the tool further comprising a stop preventing an escaping movement of the pressure element, 
 
       the method comprising the steps of:
 introducing the anchoring element into the receiving part until the head is seated in the seat, 
 introducing the pressure element into the receiving part and aligning the U-shaped recess and the channel for receiving the rod, 
 engaging the counter-holding member with the receiving part, 
 contacting the stop with the pressure element, 
 engaging the drive member with the head recess, 
 and driving the shaft into the bone. 
 
     
     
       17. A bone anchoring device comprising:
 an anchoring element having a shaft for anchoring to a bone and having a head; 
 a receiving part formed in one piece, the receiving part comprising a seat for receiving the head and a channel for receiving a rod to be connected to the bone anchoring device; 
 a pressure element formed in one piece, the pressure element being movable in the receiving part and configured to exert pressure onto the head, the pressure element comprising a substantially U-shaped recess defining a bottom and two side walls to receive the rod therebetween; and 
 wherein the anchoring element is pivotable with respect to the receiving part and configured to be fixed at an angle by exerting pressure via the pressure element onto the head; 
 wherein the pressure element comprises a spring element configured to engage a portion of the receiving part so that the pressure element can be held in a position that allows pivoting of the anchoring element; and 
 wherein the spring element is monolithic with an outer wall portion of one side wall of the two side walls and the spring element is spaced apart from an inner wall portion of the one side wall by a slot, the slot being entirely closed when viewed in a cross-section through the bottom and the two side walls of the pressure element. 
 
     
     
       18. A bone anchoring device comprising:
 an anchoring element having a shaft for anchoring to a bone and having a head; 
 a receiving part formed in one piece, the receiving part comprising a seat for receiving the head and a channel for receiving a rod to be connected to the bone anchoring device; 
 a pressure element formed in one piece, the pressure element being movable in the receiving part and configured to exert pressure onto the head when the head and the pressure element are in the receiving part, the pressure element comprising a substantially U-shaped recess defining a curved bottom wall and two straight side walls to receive the rod therebetween; and 
 wherein the anchoring element is pivotable with respect to the receiving part and is configured to be fixed at an angle by exerting pressure via the pressure element onto the head; 
 wherein the pressure element comprises a spring element configured to engage a portion of the receiving part so that the pressure element can be held in a position that allows pivoting of the anchoring element when the head and the pressure element are in the receiving part; 
 wherein the spring element is on an outer wall portion of one of the straight side walls, the spring element spaced apart from an inner wall portion of the one straight side wall by a slot; and 
 wherein the slot is positioned in the one straight side wall.